As mobile phones, digital AV devices, IC cards and the like are highly functionalized, there is a growing demand for miniaturizing and thinning semiconductor silicon chips (hereafter referred to as “chips”) to be mounted and thereby highly integrating the chips in a package. In order to fulfill high integration of chips in a package, it is necessary to reduce the thickness of each chip to a range of 25 to 150 μm.
However, a semiconductor wafer (hereafter referred to as “wafer”) on which chips are based is thinned by grinding, and therefore decreases in strength. The decrease in strength is likely to cause a crack or a warpage in the wafer. Furthermore, it is difficult to automatically convey such a wafer having decreased in strength due to a decrease in thickness. Therefore, it is necessary to manually convey the wafer, and it is troublesome to handle the wafer.
For this reason, a wafer support system has been developed for keeping the strength of a wafer by attaching a support plate to a wafer to be ground and for thereby preventing a crack and a warpage in the wafer. The “support plate” here means a plate composed of glass, hard plastic, or the like. The wafer support system makes it possible to keep the strength of a wafer. This makes it possible to automatically convey a semiconductor wafer having been made thinner.
A support plate is attached to a wafer with use of an adhesive tape, a thermoplastic resin, an adhesive, or the like. After the wafer to which the support plate has been attached is made thinner, the support plate is separated from the wafer before the wafer is diced. In cases where the wafer is separated from the support plate, the wafer is usually separated from the support plate by ripping down the wafer from the support plate or by dissolving the resin or the adhesive with which the wafer has been attached to the support plate.
For example, Japanese Patent Application Publication, Tokukaihei, No. 11-111824 A (Publication Date: Apr. 23, 1999) discloses a method for separating a wafer from a support plate by inserting a blade edge of a scraper between the wafer and the support plate and moving the blade edge of the scraper along a surface of the support plate so as to remove an adhesive with which the wafer has been attached to the support plate. Furthermore, Japanese Patent Application Publication, Tokukai, No. 2006-32506 A (Publication Date: Feb. 2, 2006) discloses a method for separating a wafer from a support plate while preventing adhesion between the wafer and the support plate due to closure of an interface where the support plate is separated from the wafer, by inserting a blade into an adhesive material with which the support plate has been attached to the wafer and vibrating the adhesive material while biasing the wafer in a direction away from the support plate.
When a support plate is separated from a wafer having been made thinner, it is necessary to be careful not to break the wafer having been made thinner. However, since both of the methods disclosed in Japanese Patent Application Publication, Tokukaihei, No. 11-111824 A and Japanese Patent Application Publication, Tokukai, No. 2006-32506 A involve the insertion of a blade between a wafer and a support plate, it is highly possible that the wafer will be broken when the blade is inserted. Moreover, an extremely high level of location accuracy is required for securely inserting a blade between a wafer having been made thinner and a support plate. Therefore, there is a demand for the development of an apparatus capable of easily separating a support plate from a wafer without breaking the wafer.
The present invention has been made in consideration of the aforementioned problems. It is an object of the present invention to provide a separating apparatus and a separating method by each of which a support plate can be separated from a wafer to which the support plate has been attached.